Grain-oriented electric steel sheets are used mainly as iron cores for transformers and other electrical appliances, and they must have good excitation and iron loss characteristics as the magnetic properties. In recent years, miniaturization of electrical appliances, such as, transformers has become a more and more important problem, and for this purpose, it is necessary to reduce the weight of the iron cores.
In general, in order to reduce the weight of iron cores used in various electrical appliances, a high degree of magnetic flux density must be utilized so that magnetic materials having good magnetization characteristics, namely B.sub.8 characteristics are required. As compared with a magnetic material having low B.sub.8 characteristics, a magnetic material having high B.sub.8 characteristics shows a much better iron loss at a high magnetic field and shows a low increasing rate of iron loss accompanying an increase of the magnetic flux density.
In view of the above requirements, improvements of the magnetic density, which is naturally required with an increased size of electrical appliances, will be realized only by development of high magnetic flux density grain-oriented electric steel sheets.